The present invention relates to a hydraulic pump with permanent-magnet rotor having a preset direction of rotation.
Conventional hydraulic pumps are already commercially available to which bipolar permanent-magnet motors are applied. Such motors have electronic or mechanical control means which allow to turn the impeller in a specific and preset direction of rotation.
The prior art already uses, as shown in FIG. 1, impellers with curved vanes in which rotation could occur in both directions if other elements were not provided.
If the impeller, designated by the reference numeral 1, turned in the direction in which the vanes 2 are swept backward, a significant flow-rate is in fact obtained with an initial pick-up transient in which the load is constituted by the inertial load of the rotor of the impeller plus the dynamic load due to the energy transferred to the fluid.
With this arrangement, in which the volute 3 of the pump is shaped like an Archimedean spiral, if other measures were not taken the motor might start in the reverse direction, with the vanes swept forward, so that the pump, as shown schematically in FIG. 1, might operate with a greatly reduced flow-rate, i.e., it would deliver a very small flow-rate; with this arrangement, however, the negative torque would in any case be very low and therefore the motor is capable of supporting equally both directions of rotation.
The aim of the present invention is to solve the above problem, by providing a hydraulic pump with permanent-magnet motor having a preset direction of rotation which allows to obtain a single direction of rotation without having to provide electronic controls, which are particularly complicated and expensive, or mechanical antireversing protrusions which cause the typical drawbacks of breakage, wear and noise.
Within the scope of this aim, an object of the present invention is to provide a hydraulic pump in which it is possible to install larger impellers with an equivalent motor, thus obtaining better results, especially in terms of the head of the pump.
Another object of the present invention is to provide a hydraulic pump which, thanks to its particular constructive characteristics, is capable of giving the greatest assurances of reliability and safety in use.
Another object of the present invention is to provide a hydraulic pump with permanent-magnet motor having a preset direction of rotation which can be easily obtained starting from commonly commercially available elements and materials and is also competitive from a merely economical standpoint.
This aim and these and other objects which will become better apparent hereinafter are achieved by a hydraulic pump with permanent-magnet motor having a preset direction of rotation, according to the invention, which comprises a permanent-magnet motor connected to an impeller with curved vanes which is rotatably accommodated in a volute, characterized in that said volute is predominantly symmetrical with respect to a line being directed toward the intake port and passing through the rotation axis of the impeller.